Check floats for .nan

[Daniel Keep]

BCS wrote:
> Reply to acarion,
> 
>> I have this code:
>>
>> float number=getFloat();
>> assert(number!=float.nan); //this passes
> 
> IIRC this will also pass:
> 
> assert(float.nan != float.nan);
> 
> this is because D used IEEE floating point semantics. Under IEEE a
> comparison with NaN will always be  not equal
> 
> If you want to test for nan use "testedValue !<>= 0"* or the isnan function

You can also use (x!=x) to test to see if x is NaN, and (x==x) to make
sure it is not NaN.

	-- Daniel